Graphene core for a golf ball

ABSTRACT

A golf ball with a core comprising polybutadiene and graphene is disclosed herein. The golf ball has a single core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an inner core comprising polybutadiene and graphene. Alternatively, the golf ball has a dual core with an outer core comprising polybutadiene and graphene.

CROSS REFERENCES TO RELATED APPLICATIONS

The Present Application is a continuation application of U.S. patentapplication Ser. No. 15/704,220, filed on Sep. 14, 2017, which is adivisional application of U.S. patent application Ser. No. 15/436,169,filed on Feb. 17, 2017, now U.S. Pat. No. 9,789,366, issued on Oct. 17,2017, which claims priority to U.S. Provisional Patent Application No.62/401,034, filed on Sep. 28, 2016, now expired, each of which is herebyincorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention generally relates to the use of graphene in layersof a golf ball.

Description of the Related Art

Typical process of synthesizing exfoliated graphite (individual sheetsof exfoliated graphite are also known as graphene or graphenenanoplatelets) includes reacting graphite with acids such as nitric andor sulfuric acid followed by heat treatment and chemical reduction.Exfoliated graphite is a two dimensional planar sheet made ofSP²-hybridized carbon. Graphene (individual sheets of reduced exfoliatedgraphite) sheets are typically few nanometers thick and few microns wide(aspect ratio of >1000). This high aspect ratio of graphene coupled withtheir high tensile strength (tensile strength in GPa compared to MPa forpolymers) can lead to polymeric composite materials with very hightensile and flexural properties. Graphene's unusually high thermalconductivity (˜3000 W/mk compared to <1 W/mk for typical thermoplasticpolymers; can be utilized in making thermally conductive compositematerials. For thermally cured elastomeric products, this high thermalconductivity can mean shorter, more uniform curing cycles that can leadto higher production volumes.

Various examples of exfoliated graphite (also called graphene) basedcomposites can be found in literature. Wang et al. describe expandedgraphite polyethylene composite for electromagnetic radiationinterference (EMI) shielding applications.

U.S. Pat. No. 4,946,892 describes synthesis of exfoliated graphene basedcomposite by compression molding graphite with polyimide resin underhigh heat (200 C) and pressure (80 kPa).

Shioyama describes synthesis of polyisoprene and polystyrene basedcomposite materials by in-situ polymerization of styrene and isoprenemonomers in presence of exfoliated graphite.

U.S. Pat. No. 5,776,372 describes an electrically conductivenanocomposite made with expanded graphite and various polymers such aspolypropylene, polytetrafluoroethylene, and phenolic resin. Pan et al.describe synthesis of nylon-6 expanded graphite nanocomposite bypolymerization of ϵ-caprolactam in presence of expanded graphite.

Chen et al. describe in-situ polymerization of methyl methacrylate inpresence of expanded graphite to obtain an electrically conductivenanocomposite.

Xiao et al. describe making exfoliated graphite composite with improvedthermal stability by in-situ polymerization of styrene in presence ofexfoliated graphene.

The prior art fails to even recognize this problem.

BRIEF SUMMARY OF THE INVENTION

The primary purpose of the present invention is to improve durability ofgolf ball core by incorporation of graphene in the core to improve theimpact strength of the ball. This benefit can be seen in either a ballwith single piece core, or a dual core with an outer core firmer thanthe inner core. Improved durability of the core by using graphene canresult in higher mean time to fail (MTTF) upon repeated impact in a highspeed testing device, or with a golf club in normal play.

Another objective is to improve aging properties due to theincorporation of graphene in the core for better retention ofcompression and COR over time.

One aspect of the present invention is a golf ball comprising a centercore comprising polybutadiene and a graphene material in an amountranging from 0.1 to 5.0 weight percent of the center core, and a coverlayer disposed over the center core.

In a more preferred embodiment, the graphene material ranges from 0.4 to2.5 weight percent of the center core. In an even more preferredembodiment, the graphene material ranges from 0.6 to 1.5 weight percentof the center core.

Another aspect of the present invention is a golf ball comprising acenter core, an outer core, an inner mantle layer, an outer mantlelayer, and a cover. The center core comprises a polybutadiene materialand a graphene material in an amount ranging from 0.1 to 5.0 weightpercent of the center core. The outer core is disposed over the centercore. The inner mantle layer is disposed over the outer core. The innermantle layer has a thickness ranging from 0.03 inch to 0.09 inch. Theinner mantle layer is composed of an ionomer material. The inner mantlelayer material has a plaque Shore D hardness ranging from 34 to 55. Theouter mantle layer is disposed over the inner mantle layer. The outermantle layer has a thickness ranging from 0.025 inch to 0.050 inch. Thecover layer is disposed over the outer mantle layer. The cover layer hasa thickness ranging from 0.025 inch to 0.040 inch. The cover layer has alower Shore D hardness than the outer mantle layer. The outer mantlelayer has a higher Shore D hardness than the inner mantle layer. Theouter core has a higher Shore D hardness than the inner mantle layer andthe center core.

Yet another aspect of the present invention is a golf ball comprising acenter core, an outer core, an inner mantle layer, an outer mantlelayer, and a cover. The center core comprises a polybutadiene materialand a graphene material in an amount ranging from 0.1 to 5.0 weightpercent of the center core. The outer core is disposed over the centercore. The inner mantle layer is disposed over the outer core. The innermantle layer has a thickness ranging from 0.03 inch to 0.09 inch. Theinner mantle layer material has a plaque Shore D hardness ranging from30 to 50. The outer mantle layer is disposed over the inner mantlelayer. The outer mantle layer has a thickness ranging from 0.025 inch to0.070 inch. The outer mantle layer material has a plaque Shore Dhardness ranging from 50 to 71. The inner mantle is thicker than theouter mantle, and the outer mantle is harder than the inner mantle. Thecover layer is disposed over the outer mantle layer. The cover layer hasa thickness ranging from 0.025 inch to 0.050 inch. The cover layer has aShore D hardness less than the hardness of the outer mantle layer. Theouter mantle layer has a higher Shore D hardness than the inner mantlelayer. The outer core has a higher Shore D hardness than the innermantle layer and the center core.

Yet another aspect of the present invention is a golf ball comprising acenter core, an outer core, an inner mantle layer, an outer mantlelayer, and a cover. The center core comprises a polybutadiene materialand a graphene material in an amount ranging from 0.1 to 5.0 weightpercent of the center core. The outer core is disposed over the centercore. The inner mantle layer is disposed over the outer core. The innermantle layer has a thickness ranging from 0.03 inch to 0.09 inch. Theinner mantle layer material has a plaque Shore D hardness ranging from36 to 44. The outer mantle layer is disposed over the inner mantlelayer. The outer mantle layer has a thickness ranging from 0.025 inch to0.070 inch. The outer mantle layer material has a plaque Shore Dhardness ranging from 65 to 71. The inner mantle is thicker than theouter mantle, and the outer mantle is harder than the inner mantle. Thecover layer is disposed over the outer mantle layer. The cover layer hasa thickness ranging from 0.025 inch to 0.040 inch. The cover layer has alower Shore D hardness than the outer mantle layer, the outer mantlelayer has a higher Shore D hardness than the inner mantle layer, and theouter core has a higher Shore D hardness than the inner mantle layer andthe center core.

Yet another aspect of the present invention is a golf ball comprising acenter core, an inner mantle layer, a first center mantle layer, asecond center mantle layer, an outer mantle layer, and a cover. Thecenter core comprises a polybutadiene material and a graphene materialin an amount ranging from 0.1 to 5.0 weight percent of the center core.The inner mantle layer is disposed over the center core. The innermantle layer has a thickness ranging from 0.030 inch to 0.050 inch. Theinner mantle layer material has a plaque Shore D hardness ranging from30 to 40. The inner mantle layer is composed of a composed of an ionomermaterial. The first center mantle layer is disposed over the innermantle layer. The first center mantle layer has a thickness ranging from0.030 inch to 0.050 inch. The first center mantle layer material has aplaque Shore D hardness ranging from 40 to 55. The first center mantlelayer is composed of a fully neutralized polymer material. The secondcenter mantle layer is disposed over the second center mantle layer. Thesecond center mantle layer has a thickness ranging from 0.030 inch to0.050 inch. The second center mantle layer material has a plaque Shore Dhardness ranging from 45 to 55. The second center mantle layer iscomposed of a fully neutralized polymer material. The outer mantle layeris disposed over the second center mantle layer. The outer mantle layerhas a thickness ranging from 0.030 inch to 0.050 inch. The outer mantlelayer is composed of an ionomer material. The outer mantle layermaterial has a plaque Shore D hardness ranging from 60 to 75. The coverlayer is disposed over the outer mantle layer, and has a thicknessranging from 0.025 inch to 0.040 inch.

Yet another aspect of the present invention is a golf ball comprising acenter core, an inner mantle layer, a first center mantle layer, asecond center mantle layer, an outer mantle layer, and a cover. Thecenter core comprises a polybutadiene material and a graphene materialin an amount ranging from 0.1 to 5.0 weight percent of the center core.The inner mantle layer is disposed over the center core. The innermantle layer has a thickness ranging from 0.030 inch to 0.050 inch. Theinner mantle layer material has a plaque Shore D hardness ranging from30 to 40. The inner mantle layer is composed of a composed of an ionomermaterial. The first center mantle layer is disposed over the innermantle layer. The first center mantle layer has a thickness ranging from0.030 inch to 0.050 inch. The first center mantle layer material has aplaque Shore D hardness ranging from 40 to 55. The first center mantlelayer is composed of a fully neutralized polymer material. The secondcenter mantle layer is disposed over the second center mantle layer. Thesecond center mantle layer has a thickness ranging from 0.030 inch to0.050 inch. The second center mantle layer material has a plaque Shore Dhardness ranging from 45 to 55. The second center mantle layer iscomposed of a fully neutralized polymer material. The outer mantle layeris disposed over the second center mantle layer. The outer mantle layerhas a thickness ranging from 0.030 inch to 0.050 inch. The outer mantlelayer is composed of an ionomer material. The outer mantle layermaterial has a plaque Shore D hardness ranging from 60 to 75. The coverlayer is disposed over the outer mantle layer, and has a thicknessranging from 0.025 inch to 0.040 inch.

A yet another aspect of the present invention is a method for forming acore for a golf ball. The method includes mixing a graphene materialwith a polybutadiene material to form a core mixture, wherein thegraphene material ranges from 0.1 to 5.0 weight percent of the coremixture. The method also includes compression molding a core from thecore mixture. The core preferably has a diameter ranging from 0.70 inchto 1.6 inch. The core mixture preferably comprises 40-90 weight percentof polybutadiene, 0.4 to 2.5 weight percent graphene material, 1-30weight percent polyisoprene, 10-50 weight percent zinc diacrylate, 1-30weight percent zinc oxide, 1-20 weight percent zinc stearate, and 0.1-10weight percent peroxide initiator.

A more preferred embodiment of the method includes forming a cover overthe core.

A more preferred embodiment of the method includes forming a mantlelayer over the core.

A more preferred embodiment of the method includes that the core mixtureis molded over an inner core to produce a dual core with a diameterranging from 0.7 inch to 1.6 inches.

A more preferred embodiment of the method includes compression molding acore from the core mixture comprises compression molding an outer corelayer over a center core comprising a polybutadiene mixture.

A more preferred embodiment of the method includes compression molding acore from the core mixture comprises compression molding a center coreand an outer core over the center core, and the center core and theouter core comprise the core mixture.

Yet another aspect of the invention is a golf ball comprising an innercore, an outer core comprising a polybutadiene and a graphene materialin an amount ranging from 0.1 to 5.0 weight percent of the outer core, amantle layer and a cover.

Yet another aspect of the invention is a golf ball comprising an innercore comprising a polybutadiene and a graphene material in an amountranging from 0.1 to 5.0 weight percent of the inner core, an outer corecomprising a polybutadiene and a graphene material in an amount rangingfrom 0.1 to 5.0 weight percent of the outer core, a mantle layer, and acover.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an exploded partial cut-away view of a golf ball.

FIG. 2 is top perspective view of a golf ball.

FIG. 3 is a cross-sectional view of a core component of a golf ball.

FIG. 4 is a cross-sectional view of a core component and a mantlecomponent of a golf ball.

FIG. 5 is a cross-sectional view of an inner core layer, an outer corelayer, an inner mantle layer, an outer mantle layer and a cover layer ofa golf ball.

FIG. 5A is a cross-sectional view of an inner core layer, anintermediate core layer, an outer core layer, a mantle layer and a coverlayer of a golf ball.

FIG. 6 is a cross-sectional view of an inner core layer under a 100kilogram load.

FIG. 7 is a cross-sectional view of a core under a 100 kilogram load.

FIG. 8 is a cross-sectional view of a core component and a mantlecomponent of a golf ball.

FIG. 9 is a cross-sectional view of a core component, the mantlecomponent and a cover layer of a golf ball.

FIG. 10 is an exploded partial cut-away view of a four-piece golf ball.

FIG. 11 is an exploded partial cut-away view of a three-piece golf ball.

FIG. 12 is an exploded partial cut-away view of a two-piece golf ball.

FIG. 13 is a cross-sectional view of a two-piece golf ball.

FIG. 14 is a cross-sectional view of a three-piece golf ball.

FIG. 15 is an exploded partial cut-away view of a three-piece golf ball.

FIG. 16 is a cross-sectional view of a three-piece golf ball with a dualcore and a cover.

FIG. 17 is a cross-sectional view of a three-piece golf ball with acore, mantle and cover.

FIG. 18 is a cross-sectional view of a four-piece golf ball with a dualcore, mantle layer and a cover.

FIG. 19 is a cross-sectional view of a four-piece golf ball with a core,dual mantle layers and a cover.

FIG. 20 is a graph of durability testing of outer cores using PTM at 175fps.

FIG. 21 is a graph of durability testing of dual cores using PTM at 175fps.

FIG. 22 is a graph of durability testing of dual cores using PTM at 175fps.

FIG. 23 is a graph of durability testing of dual cores using PTM at 175fps.

FIG. 24 is an illustration of graphene.

DETAILED DESCRIPTION OF THE INVENTION

One objective of the present invention is to improve durability of golfball core by incorporation of graphene in either the core the impactstrength of the ball. This benefit can be seen in either a ball designedto have a low compression single piece core, or a dual core with anouter core firmer than the inner core. Improved durability of the coreor mantle composition by using graphene can result in higher mean timeto fail (MTTF) upon repeated impact in a high speed testing device, orwith a golf club in normal play.

Another objective of the present invention is to improve agingproperties due to the incorporation of graphene in either the core ormantle layer for better retention of compression and COR over time.

Polybutadiene based cores were made using following materials.Corresponding levels (by % wt) is mentioned next to each material:Polybutadiene with more than 60% 1,4-cis structure—(40-90%);Polyisoprene—(1-30%); Zinc diacrylate—(10-50%); Zinc oxide—(1-30%); Zincstearate—(1-20%); Peroxide initiator—(0.1-10%); Zincpentachlorothiophenol—(0-10%); Color—(0-10%); Barium sulfate—(0-20%);Graphene—(0.01-6%)—available from various suppliers such as Cheap TubesInc., Ad-Nano Technologies Private Limited, MKnano, XG Sciences Inc.,Angstron Materials Inc.; Graphene masterbatch (a masterbatch of 90-99%polybutadiene or polyisoprene and 1-10% graphene)—(0.1-50%)—customcompounding can be done with the help of various suppliers such asPreferred Compounding Corp, Dyna-Mix, Alttran, Callaway (in housecompounding).

Four different single cores (formula 1 to 4) were made as shown inrecipe in Table 1. Control group (formula 1) had no graphene

TABLE 1 Recipe of solid core (graphene) Formula 1 Formula 2 Formula 3Formula (0% (0.4% (0.8% 4(1.6% Graphene) Graphene) Graphene) Graphene)Components % wt % wt % wt % wt Polybutadiene 62.5 62.3 62.1 61.5 ZincDiacrylate 19.9 19.8 19.7 19.6 Zinc Oxide 6.3 6.2 6.2 6.2 Zinc Stearate3.8 3.7 3.7 3.7 Peroxide initiator 0.5 0.5 0.5 0.5 Zinc 0.6 0.6 0.6 0.6pentachlorothiophenol Color 0.1 0.1 0.1 0.1 Limestone 0.0 0.0 0.0 0.0Tungsten 0.0 0.0 0.0 0.0 Barium sulfate 6.4 6.4 6.4 6.3 Graphene 0.0 0.40.8 1.6 Graphene in masterbatch 0.0 0.0 0.0 0.0 Properties of coreCompression 69.4 74.3 74.6 76.4 COR (coefficient of 0.801 0.800 0.7950.790 restitution @125 fps) Durability score or mean 34 60 47 62 time tofail MTTF (number of shots after which ball starts to crack/fail)

Compression is measured by applying a 200 pound load to the core andmeasuring its deflection, in inches. Compression=180−(deflection*1000).

Durability Testing of Solid Cores

Cores were shot at 150 fps in a pneumatic testing machine (PTM).

For each formula mentioned in Table 1, 12 cores were tested. Number ofshots after which each core cracked was recorded for each core, and thecracked core was removed from the remainder of the test. The data wasreported using a Weibull plot, and the mean time to fail was reported asshown in Table 1. As seen in FIG. 20, graphene modified cores enduredmore shots before failure compared to cores with no graphene. It isreasonable to assume that the durability of a golf ball having a singlepiece core of this design will also experience a dramatic increase incrack durability based on this improvement to the core.

Dual Cores with Graphene Only in the Outer Core.

In this study graphene was introduced to the outer core in a dual coreconstruction. Dual cores were made by compression molding two outer corehalves around an already molded inner core having a diameter ofapproximately 0.940″ and a soft compression of approximately 0.200inches of deflection under a 200 lb load. Curing of the inner and outercore was done at temperatures ranging between 150-400° F. for timesranging from 1-30 minutes. After molding, the dual cores werespherically ground to approximately 1.554″ prior to testing.

Table 2 and 3 give details of recipe of inner and outer cores.Components from these recipes were mixed in an internal mixer.Optionally, additional mixing was done using a two roll mill.

Compression of the outer core is measured by first making a full sizecore separately, measuring its compression, and then molding two halvesaround the inner core to complete the dual core.

Compression differential describes the difference between the outer corecompression (as molded independently) and inner core compression. Ahigher compression differential is more susceptible to crack durabilityupon impact.

TABLE 2 Inner core recipe Components % wt Polybutadiene rubber 69.2Polyisoprene rubber 0.0 Zinc diacrylate 14.8 Zinc oxide 12.2 Zincstearate 2.1 Peroxide initiator 1.0 Zinc pentachlorothiophenol 0.6 Color0.1 Barium sulfate 0.0 graphene 0.0 graphene masterbatch 0.0 PropertiesCompression 0.220

TABLE 3 Outer core recipe of dual core Formula 5 Formula 6 Formula 7Formula 8 (0% (0.4% (0.8% (1.6% Graphene) Graphene) Graphene) Graphene)Components % wt % wt % wt % wt Polybutadiene 62.5 62.3 62.1 61.5 ZincDiacrylate 19.9 19.8 19.7 19.6 Zinc Oxide 6.3 6.2 6.2 6.2 Zinc Stearate3.8 3.7 3.7 3.7 Peroxide initiator 0.5 0.5 0.5 0.5 Zinc 0.6 0.6 0.6 0.6pentachlorothiophenol Color 0.1 0.1 0.1 0.1 Limestone 0.0 0.0 0.0 0.0Tungsten 0.0 0.0 0.0 0.0 Barium sulfate 6.4 6.4 6.4 6.3 Graphene 0.0 0.40.8 1.6 Graphene in masterbatch 0.0 0.0 0.0 0.0 Properties of outer coreCompression 69.4 74.3 74.6 76.4 COR (coefficient of 0.801 0.800 0.7950.790 restitution) Properties of dual core built from inner and outercore Compression 48.9 50.9 52.1 54.1 COR (coefficient of 0.796 0.7950.793 0.790 restitution @125 fps) Durability score or mean 50 60 52 57time to fail MTTF (number of shots after which ball starts tocrack/fail)

Compression is measured by applying a 200 pound load to the core andmeasuring its deflection, in inches. Compression=180−(deflection*1000)

Durability Testing of Dual Cores

Cores were shot at 175 fps in a pneumatic testing machine (PTM).

For each formula mentioned in Table 3, 12 cores were tested. Number ofshots after which each core cracked was recorded for each core, and thecracked core was removed from the remainder of the test. The data wasreported using a Weibull plot, and the mean time to fail was reported asshown in Table 3. As seen in FIG. 21, graphene modified cores enduredmore shots before failure compared to cores with no graphene. It isreasonable to assume that the durability of a golf ball having a dualcore of this design will also experience a dramatic increase in crackdurability based on this improvement to the dual core. It's reasonableto assume that the addition of graphene in the inner core could providea durability enhancement to the overall golf ball, but this study onlyfocused on the outer core.

Dual Cores with Graphene-2 in Outer Core Only

In this study Graphene-2 (—(0.01-6%)—available from various supplierssuch as Cheap Tubes Inc., Ad-Nano Technologies Private Limited, MKnano,XG Sciences Inc., Angstron Materials Inc which has a surface areabetween 150-1000 m²/g) was introduced to the outer core in a dual coreconstruction. Dual cores were made by compression molding two outer corehalves around an already molded inner core having a diameter ofapproximately 0.940″ and a soft compression of approximately 0.200inches of deflection under a 200 lb load. Curing of the inner and outercore was done at temperatures ranging between 150-400 F for timesranging from 1-30 minutes. After molding, the dual cores werespherically ground to approximately 1.554″ prior to testing.

Tables 4 and 5 give details of recipe of inner and outer cores.Components from these recipes were mixed in an internal mixer.Optionally, additional mixing was done using a two roll mill.

Compression of the outer core is measured by first making a full sizecore separately, measuring its compression, and then molding two halvesaround the inner core to complete the dual core. Compressiondifferential describes the difference between the outer core compression(as molded independently) and inner core compression. A highercompression differential is more susceptible to crack durability uponimpact.

TABLE 4 Table 4. Inner core recipe Components % wt Polybutadiene rubber69.2 Polyisoprene rubber 0.0 Zinc diacrylate 14.8 Zinc oxide 12.2 Zincstearate 2.1 Peroxide initiator 1.0 Zinc pentachlorothiophenol 0.6 Color0.1 Barium sulfate 0.0 Graphene-2 0.0 Graphene-2 masterbatch 0.0Properties Compression 0.220 inch under 200 lb load

TABLE 5 Table 5. Outer recipe of dual core Formula Formula FormulaFormula 9 10 11 12 (0% (0.4% (0.8% (1.6% Graphene) Graphene) Graphene)Graphene) Components % wt % wt % wt % wt Polybutadiene 62.5 62.3 62.061.6 Zinc Diacrylate 19.9 19.8 19.7 19.6 Zinc Oxide 6.3 6.2 6.2 6.2 ZincStearate 3.8 3.7 3.7 3.7 Peroxide initiator 0.5 0.5 0.5 0.5 Zinc 0.6 0.60.6 0.6 pentachlorothiophenol Color 0.1 0.1 0.1 0.1 Limestone 0.0 0.00.0 0.0 Tungsten 0.0 0.0 0.0 0.0 Barium sulfate 6.4 6.4 6.4 6.3Graphene-2 0.0 0.4 0.8 1.6 Graphene-2 in 0.0 0.0 0.0 0.0 masterbatchProperties of outer core Compression 67.0 69.1 68.8 70.8 COR(coefficient of 0.801 0.798 0.795 0.791 restitution) Properties of dualcore built from inner and outer core Compression 45.0 48.9 48.6 50.4 COR(coefficient of 0.795 0.794 0.793 0.789 restitution @125 fps) Durabilityscore or mean 33 67 78 99 time to fail MTTF (number of shots after whichball starts to crack/fail)

Compression is measured by applying a 200 pound load to the core andmeasuring its deflection, in inches. Compression=180−(deflection*1000).

Durability Testing of Dual Cores

Cores were shot at 175 fps in a pneumatic testing machine (PTM).

For each formula mentioned in Table 5, 12 cores were tested. Number ofshots after which each core cracked was recorded for each core, and thecracked core was removed from the remainder of the test. The data wasreported using a Weibull plot, and the mean time to fail was reported asshown in Table 5. Testing was stopped after 100 shots. As shown in FIG.22, graphene modified cores endured more shots before failure comparedto cores with no graphene. It is reasonable to assume that thedurability of a golf ball having a dual core of this design will alsoexperience a dramatic increase in crack durability based on thisimprovement to the dual core. It's reasonable to assume that theaddition of graphene in the inner core could provide a durabilityenhancement to the overall golf ball, but this study only focused on theouter core.

Dual Cores with Graphene in the Inner Core and the Outer Core.

In this study graphene was introduced to the inner and outer core in adual core construction. Table 6 gives details of recipe of inner andouter cores of these dual cores. Components from these recipes weremixed in an internal mixer. Optionally, additional mixing was done usinga two roll mill. Dual cores were made by compression molding two outercore halves around an already molded inner core having a diameter ofapproximately 0.940″ and a soft compression of approximately 0.200inches of deflection under a 200 lb load. Curing of the inner and outercore was done at temperatures ranging between 150-400 F for timesranging from 1-30 minutes. After molding, the dual cores werespherically ground to approximately 1.554″ prior to testing.

Compression of the outer core was measured by first making a full sizecore separately, measuring its compression, and then molding two halvesaround the inner core to complete the dual core.

TABLE 6 Table 6. Dual core recipes with graphene in the inner core andthe outer core Formula Formula Formula Formula 13- 14- 15- 16- innercore inner core inner core inner core Components % wt % wt % wt % wtPolybutadiene 69.2 69.2 69.1 68.9 Zinc Diacrylate 14.8 14.8 14.7 14.7Zinc Oxide 12.3 12.3 12.2 12.2 Zinc Stearate 2.1 2.1 2.1 2.1 Peroxideinitiator 1.0 1.0 1.0 1.0 Zinc 0.6 0.6 0.6 0.6 pentachlorothiophenolColor 0.0 0.0 0.0 0.0 Limestone 0.0 0.0 0.0 0.0 Tungsten 0.0 0.0 0.0 0.0Barium sulfate 0.0 0.0 0.0 0.0 Graphene 0.0 0.0 0.2 0.4 Properties ofinner core Compression 0.221 0.221 0.219 0.217 Formula Formula FormulaFormula 13- 14- 15- 16- outer core outer core outer core outer coreComponents % wt % wt % wt % wt Polybutadiene 62.5 62.3 62.3 62.3 ZincDiacrylate 19.9 19.8 19.8 19.8 Zinc Oxide 6.2 6.2 6.2 6.2 Zinc Stearate3.7 3.7 3.7 3.7 Peroxide initiator 0.5 0.5 0.5 0.5 Zinc 0.6 0.6 0.6 0.6pentachlorothiophenol Color 0.1 0.0 0.0 0.0 Limestone 0.0 0.0 0.0 0.0Tungsten 0.0 0.0 0.0 0.0 Barium sulfate 6.5 6.5 6.5 6.5 Graphene 0.0 0.40.4 0.4 Properties of outer core Compression 67.8 67.6 67.6 67.6 COR(coefficient of 0.800 0.796 0.796 0.796 restitution @125 fps) Propertiesof dual core built from inner and outer core Compression 47.3 48.1 49.048.3 COR (coefficient of 0.795 0.793 0.793 0.792 restitution @125 fps)Durability score or mean 29 24 33 40 time to fail MTTF (number of shotsafter which ball starts to crack/fail)

Compression is measured by applying a 200 pound load to the core andmeasuring its deflection, in inches. Compression=180−(deflection*1000).

For each formula mentioned in Table 6, 12 cores were tested. Number ofshots after which each core cracked was recorded for each core, and thecracked core was removed from the remainder of the test. The data wasreported using a Weibull plot, and the mean time to fail was reported asshown in Table 6. As seen in FIG. 23, graphene modified cores enduredmore shots before failure compared to cores with no graphene. The bestdurability was observed for balls which had graphene in inner and outercores. It is reasonable to assume that the durability of a golf ballhaving a dual core of this design will also experience a dramaticincrease in crack durability based on this improvement to the dual core.It's reasonable to assume that the addition of graphene in the innercore could provide a durability enhancement to the overall golf ball,but this study only focused on the outer core.

Novelty of this process: Durability of the dual core with a highcompression differential is greatly enhanced by incorporation ofgraphene in inner and outer core. The graphene reinforcement to theinner and outer core helps resist the high stresses experienced by thecore when struck at high club speeds. Addition of graphene to the corerecipe is very simple and it can be dispersed into the polybutadienemixture during two roll milling process. Due to high thermalconductivity of graphene, overall thermal conductivity of cores can beincreased with incorporation of graphene. With higher thermalconductivity of graphene reinforced cores, curing cycles can be madeshorter. Shorter curing cycles can lead to higher output in production.Optionally, graphene can be introduced as a masterbatch in polybutadieneor polyisoprene, making its dispersion into polybutadiene rubber mucheasier and dust free.

Dual Core

As our experiment has shown, incorporating graphene into the inner andouter core recipe reinforces the strength of the outer core and providesgreater crack durability protection in the design of a dual core golfball, which is more susceptible to crack durability failures if theouter core is much firmer than the soft inner core.

In general, this is applicable when the inner core is softer than theouter core. More specifically, when the inner core has more than 0.200″deflection under a 200 lb load, and the dual core is 40 compression orgreater.

This is particularly crucial if the ball is a 4-piece construction witha single mantle layer with thickness less than 0.050″, or morespecifically thinner than 0.040″, with 0.036″ being the target in thisstudy.

FIGS. 1, 3, 4 and 5 illustrate a five piece golf ball 10 comprising aninner core 12 a, an outer core 12 b, an inner mantle 14 a, an outermantle 14 b, and a cover 16, wherein the cover layer 16 is composed of athermoplastic polyurethane and has a Shore A hardness less than 90. Theinner core 12 a comprises polybutadiene mixture comprising 0.4 to 2.5weight percent of a graphene.

FIG. 5A illustrates a five piece golf ball 10 comprising an inner core12 a, an intermediate core 12 b, an outer core 12 c, a mantle 14, and acover 16, wherein the cover layer 16 is composed of a thermoplasticpolyurethane. The intermediate core 12 b comprises polybutadiene mixturecomprising 0.4 to 2.5 weight percent of a graphene.

FIGS. 8 and 9 illustrate a six piece golf ball 10 comprising an innercore 12 a, an intermediate core 12 b, an outer core 12 c, an innermantle 14 a, an outer mantle 14 b, and a cover 16, wherein the coverlayer 16 is composed of a thermoplastic polyurethane. The inner core 12a comprises polybutadiene mixture comprising 0.4 to 2.5 weight percentof a graphene.

FIG. 10 illustrates a four piece golf ball comprising a dual core, aboundary layer and a cover. The outer core comprises polybutadienemixture comprising 0.4 to 2.5 weight percent of a graphene.

FIG. 11 illustrates a three piece golf ball comprising a core, aboundary layer and a cover. The core comprises polybutadiene mixturecomprising 0.4 to 2.5 weight percent of a graphene.

FIGS. 12 and 13 illustrate a two piece golf ball 20 with a core 25 and acover 30. The core comprises polybutadiene mixture comprising 0.4 to 2.5weight percent of a graphene.

FIGS. 14 and 15 illustrate a three-piece golf ball 5 comprising a core10, a mantle layer 14 and a cover 16 with dimples 18, wherein the corecomprises 0.4 to 2.5 weight percent of a graphene.

FIG. 16 illustrates a dual core three piece golf ball 35 comprising aninner core 30, and outer core 32 and a cover 34, wherein the corecomprises 0.4 to 2.5 weight percent of a graphene.

FIG. 17 illustrates a three piece golf ball 45 comprising a core 40, amantle layer 42 and a cover 44, wherein the core comprises 0.4 to 2.5weight percent of a graphene.

FIG. 18 illustrates a dual core four piece golf ball 55 comprising aninner core 50, an outer core 52, a mantle layer 54 and a cover 56,wherein the core comprises 0.4 to 2.5 weight percent of a graphene.

FIG. 19 illustrates a four piece golf ball 65 comprising a core 60, aninner mantle 62, an outer mantle 64 and a cover 66, wherein the corecomprises 0.4 to 2.5 weight percent of a graphene.

The mantle component is preferably composed of the inner mantle layerand the outer mantle layer. The mantle component preferably has athickness ranging from 0.05 inch to 0.15 inch, and more preferably from0.06 inch to 0.08 inch. The outer mantle layer is preferably composed ofa blend of ionomer materials. One preferred embodiment comprises SURLYN9150 material, SURLYN 8940 material, a SURLYN AD1022 material, and amasterbatch. The SURLYN 9150 material is preferably present in an amountranging from 20 to 45 weight percent of the cover, and more preferably30 to 40 weight percent. The SURLYN 8945 is preferably present in anamount ranging from 15 to 35 weight percent of the cover, morepreferably 20 to 30 weight percent, and most preferably 26 weightpercent. The SURLYN 9945 is preferably present in an amount ranging from30 to 50 weight percent of the cover, more preferably 35 to 45 weightpercent, and most preferably 41 weight percent. The SURLYN 8940 ispreferably present in an amount ranging from 5 to 15 weight percent ofthe cover, more preferably 7 to 12 weight percent, and most preferably10 weight percent.

SURLYN 8320, from DuPont, is a very-low modulus ethylene/methacrylicacid copolymer with partial neutralization of the acid groups withsodium ions. SURLYN 8945, also from DuPont, is a high acidethylene/methacrylic acid copolymer with partial neutralization of theacid groups with sodium ions. SURLYN 9945, also from DuPont, is a highacid ethylene/methacrylic acid copolymer with partial neutralization ofthe acid groups with zinc ions. SURLYN 8940, also from DuPont, is anethylene/methacrylic acid copolymer with partial neutralization of theacid groups with sodium ions.

The inner mantle layer is preferably composed of a blend of ionomers,preferably comprising a terpolymer and at least two high acid (greaterthan 18 weight percent) ionomers neutralized with sodium, zinc,magnesium, or other metal ions. The material for the inner mantle layerpreferably has a Shore D plaque hardness ranging preferably from 35 to77, more preferably from 36 to 44, a most preferably approximately 40.The thickness of the outer mantle layer preferably ranges from 0.025inch to 0.050 inch, and is more preferably approximately 0.037 inch. Themass of an insert including the dual core and the inner mantle layerpreferably ranges from 32 grams to 40 grams, more preferably from 34 to38 grams, and is most preferably approximately 36 grams. The innermantle layer is alternatively composed of a HPF material available fromDuPont. Alternatively, the inner mantle layer 14 b is composed of amaterial such as disclosed in Kennedy, III et al., U.S. Pat. No.7,361,101 for a Golf Ball And Thermoplastic Material, which is herebyincorporated by reference in its entirety.

The outer mantle layer is preferably composed of a blend of ionomers,preferably comprising at least two high acid (greater than 18 weightpercent) ionomers neutralized with sodium, zinc, or other metal ions.The blend of ionomers also preferably includes a masterbatch. Thematerial of the outer mantle layer preferably has a Shore D plaquehardness ranging preferably from 55 to 75, more preferably from 65 to71, and most preferably approximately 67. The thickness of the outermantle layer preferably ranges from 0.025 inch to 0.040 inch, and ismore preferably approximately 0.030 inch. The mass of the entire insertincluding the core, the inner mantle layer and the outer mantle layerpreferably ranges from 38 grams to 43 grams, more preferably from 39 to41 grams, and is most preferably approximately 41 grams.

In an alternative embodiment, the inner mantle layer is preferablycomposed of a blend of ionomers, preferably comprising at least two highacid (greater than 18 weight percent) ionomers neutralized with sodium,zinc, or other metal ions. The blend of ionomers also preferablyincludes a masterbatch. In this embodiment, the material of the innermantle layer has a Shore D plaque hardness ranging preferably from 55 to75, more preferably from 65 to 71, and most preferably approximately 67.The thickness of the outer mantle layer preferably ranges from 0.025inch to 0.040 inch, and is more preferably approximately 0.030 inch.Also in this embodiment, the outer mantle layer 14 b is composed of ablend of ionomers, preferably comprising a terpolymer and at least twohigh acid (greater than 18 weight percent) ionomers neutralized withsodium, zinc, magnesium, or other metal ions. In this embodiment, thematerial for the outer mantle layer 14 b preferably has a Shore D plaquehardness ranging preferably from 35 to 77, more preferably from 36 to44, a most preferably approximately 40. The thickness of the outermantle layer preferably ranges from 0.025 inch to 0.100 inch, and morepreferably ranges from 0.070 inch to 0.090 inch.

In yet another embodiment wherein the inner mantle layer is thicker thanthe outer mantle layer and the outer mantle layer is harder than theinner mantle layer, the inner mantle layer is composed of a blend ofionomers, preferably comprising a terpolymer and at least two high acid(greater than 18 weight percent) ionomers neutralized with sodium, zinc,magnesium, or other metal ions. In this embodiment, the material for theinner mantle layer has a Shore D plaque hardness ranging preferably from30 to 77, more preferably from 30 to 50, and most preferablyapproximately 40. In this embodiment, the material for the outer mantlelayer has a Shore D plaque hardness ranging preferably from 40 to 77,more preferably from 50 to 71, and most preferably approximately 67. Inthis embodiment, the thickness of the inner mantle layer preferablyranges from 0.030 inch to 0.090 inch, and the thickness of the outermantle layer ranges from 0.025 inch to 0.070 inch.

Preferably the inner core has a diameter ranging from 0.75 inch to 1.20inches, more preferably from 0.85 inch to 1.05 inch, and most preferablyapproximately 0.95 inch. Preferably the inner core 12 a has a Shore Dhardness ranging from 20 to 50, more preferably from 25 to 40, and mostpreferably approximately 35. Preferably the inner core has a massranging from 5 grams to 15 grams, 7 grams to 10 grams and mostpreferably approximately 8 grams.

Preferably the outer core has a diameter ranging from 1.25 inch to 1.55inches, more preferably from 1.40 inch to 1.5 inch, and most preferablyapproximately 1.5 inch. Preferably the outer core has a Shore D surfacehardness ranging from 40 to 65, more preferably from 50 to 60, and mostpreferably approximately 56. Preferably the outer core is formed from apolybutadiene, zinc diacrylate, zinc oxide, zinc stearate, a peptizerand peroxide. Preferably the combined inner core and outer core have amass ranging from 25 grams to 35 grams, 30 grams to 34 grams and mostpreferably approximately 32 grams.

Preferably the inner core has a deflection of at least 0.230 inch undera load of 220 pounds, and the core has a deflection of at least 0.080inch under a load of 200 pounds. As shown in FIGS. 6 and 7, a mass 50 isloaded onto an inner core and a core. As shown in FIGS. 6 and 7, themass is 100 kilograms, approximately 220 pounds. Under a load of 100kilograms, the inner core preferably has a deflection from 0.230 inch to0.300 inch. Under a load of 100 kilograms, preferably the core has adeflection of 0.08 inch to 0.150 inch. Alternatively, the load is 200pounds (approximately 90 kilograms), and the deflection of the core 12is at least 0.080 inch. Further, a compressive deformation from abeginning load of 10 kilograms to an ending load of 130 kilograms forthe inner core ranges from 4 millimeters to 7 millimeters and morepreferably from 5 millimeters to 6.5 millimeters. The dual coredeflection differential allows for low spin off the tee to providegreater distance, and high spin on approach shots.

In an alternative embodiment of the golf ball shown in FIG. 5A, the golfball 10 comprises an inner core 12 a, an intermediate core 12 b, anouter core 12 b, a mantle 14 and a cover 16. The golf ball 10 preferablyhas a diameter of at least 1.68 inches, a mass ranging from 45 grams to47 grams, a COR of at least 0.79, a deformation under a 100 kilogramloading of at least 0.07 mm.

In one embodiment, the golf ball comprises a core, a mantle layer and acover layer. The core comprises an inner core sphere, an intermediatecore layer and an outer core layer. The intermediate core layer iscomposed of a highly neutralized ionomer and has a Shore D hardness lessthan 40. The outer core layer is composed of a highly neutralizedionomer and has a Shore D hardness less than 45. A thickness of theintermediate core layer is greater than a thickness of the outer corelayer. The mantle layer is disposed over the core, comprises an ionomermaterial and has a Shore D hardness greater than 55. The cover layer isdisposed over the mantle layer comprises a thermoplastic polyurethanematerial and has a Shore A hardness less than 100. The golf ball has adiameter of at least 1.68 inches. The mantle layer is harder than theouter core layer, the outer core layer is harder than the intermediatecore layer, the intermediate core layer is harder than the inner coresphere, and the cover layer is softer than the mantle layer.

In another embodiment, shown in FIGS. 8 and 9, the golf ball 10 has amulti-layer core and multi-layer mantle. The golf ball includes a core,a mantle component and a cover layer. The core comprises an inner coresphere, an intermediate core layer and an outer core layer. The innercore sphere comprises a TPEE material and has a diameter ranging from0.875 inch to 1.4 inches. The intermediate core layer is composed of ahighly neutralized ionomer and has a Shore D hardness less than 40. Theouter core layer is composed of a highly neutralized ionomer and has aShore D hardness less than 45. A thickness of the intermediate corelayer is greater than a thickness of the outer core layer 12 c. Theinner mantle layer is disposed over the core, comprises an ionomermaterial and has a Shore D hardness greater than 55. The outer mantlelayer is disposed over the inner mantle layer, comprises an ionomermaterial and has a Shore D hardness greater than 60. The cover layer isdisposed over the mantle component, comprises a thermoplasticpolyurethane material and has a Shore A hardness less than 100. The golfball has a diameter of at least 1.68 inches. The outer mantle layer isharder than the inner mantle layer, the inner mantle layer is harderthan the outer core layer, the outer core layer is harder than theintermediate core layer, the intermediate core layer is harder than theinner core sphere, and the cover layer is softer than the outer mantlelayer.

In a particularly preferred embodiment of the invention, the golf ballpreferably has an aerodynamic pattern such as disclosed in Simonds etal., U.S. Pat. No. 7,419,443 for a Low Volume Cover For A Golf Ball,which is hereby incorporated by reference in its entirety.Alternatively, the golf ball has an aerodynamic pattern such asdisclosed in Simonds et al., U.S. Pat. No. 7,338,392 for An AerodynamicSurface Geometry For A Golf Ball, which is hereby incorporated byreference in its entirety.

Various aspects of the present invention golf balls have been describedin terms of certain tests or measuring procedures. These are describedin greater detail as follows.

As used herein, “Shore D hardness” of the golf ball layers is measuredgenerally in accordance with ASTM D-2240 type D, except the measurementsmay be made on the curved surface of a component of the golf ball,rather than on a plaque. If measured on the ball, the measurement willindicate that the measurement was made on the ball. In referring to ahardness of a material of a layer of the golf ball, the measurement willbe made on a plaque in accordance with ASTM D-2240. Furthermore, theShore D hardness of the cover is measured while the cover remains overthe mantles and cores. When a hardness measurement is made on the golfball, the Shore D hardness is preferably measured at a land area of thecover.

As used herein, “Shore A hardness” of a cover is measured generally inaccordance with ASTM D-2240 type A, except the measurements may be madeon the curved surface of a component of the golf ball, rather than on aplaque. If measured on the ball, the measurement will indicate that themeasurement was made on the ball. In referring to a hardness of amaterial of a layer of the golf ball, the measurement will be made on aplaque in accordance with ASTM D-2240. Furthermore, the Shore A hardnessof the cover is measured while the cover remains over the mantles andcores. When a hardness measurement is made on the golf ball, Shore Ahardness is preferably measured at a land area of the cover

The resilience or coefficient of restitution (COR) of a golf ball is theconstant “e,” which is the ratio of the relative velocity of an elasticsphere after direct impact to that before impact. As a result, the COR(“e”) can vary from 0 to 1, with 1 being equivalent to a perfectly orcompletely elastic collision and 0 being equivalent to a perfectly orcompletely inelastic collision.

COR, along with additional factors such as club head speed, club headmass, ball weight, ball size and density, spin rate, angle of trajectoryand surface configuration as well as environmental conditions (e.g.temperature, moisture, atmospheric pressure, wind, etc.) generallydetermine the distance a ball will travel when hit. Along this line, thedistance a golf ball will travel under controlled environmentalconditions is a function of the speed and mass of the club and size,density and resilience (COR) of the ball and other factors. The initialvelocity of the club, the mass of the club and the angle of the ball'sdeparture are essentially provided by the golfer upon striking. Sinceclub head speed, club head mass, the angle of trajectory andenvironmental conditions are not determinants controllable by golf ballproducers and the ball size and weight are set by the U.S.G.A., theseare not factors of concern among golf ball manufacturers. The factors ordeterminants of interest with respect to improved distance are generallythe COR and the surface configuration of the ball.

The coefficient of restitution is the ratio of the outgoing velocity tothe incoming velocity. In the examples of this application, thecoefficient of restitution of a golf ball was measured by propelling aball horizontally at a speed of 125+/−5 feet per second (fps) andcorrected to 125 fps against a generally vertical, hard, flat steelplate and measuring the ball's incoming and outgoing velocityelectronically. Speeds were measured with a pair of ballistic screens,which provide a timing pulse when an object passes through them. Thescreens were separated by 36 inches and are located 25.25 inches and61.25 inches from the rebound wall. The ball speed was measured bytiming the pulses from screen 1 to screen 2 on the way into the reboundwall (as the average speed of the ball over 36 inches), and then theexit speed was timed from screen 2 to screen 1 over the same distance.The rebound wall was tilted 2 degrees from a vertical plane to allow theball to rebound slightly downward in order to miss the edge of thecannon that fired it. The rebound wall is solid steel.

As indicated above, the incoming speed should be 125±5 fps but correctedto 125 fps. The correlation between COR and forward or incoming speedhas been studied and a correction has been made over the ±5 fps range sothat the COR is reported as if the ball had an incoming speed of exactly125.0 fps.

The measurements for deflection, compression, hardness, and the like arepreferably performed on a finished golf ball as opposed to performingthe measurement on each layer during manufacturing.

Preferably, in a five layer golf ball comprising an inner core, an outercore, an inner mantle layer, an outer mantle layer and a cover, thehardness/compression of layers involve an inner core with the greatestdeflection (lowest hardness), an outer core (combined with the innercore) with a deflection less than the inner core, an inner mantle layerwith a hardness less than the hardness of the combined outer core andinner core, an outer mantle layer with the hardness layer of the golfball, and a cover with a hardness less than the hardness of the outermantle layer. These measurements are preferably made on a finished golfball that has been torn down for the measurements.

Preferably the inner mantle layer is thicker than the outer mantle layeror the cover layer. The dual core and dual mantle golf ball creates anoptimized velocity-initial velocity ratio (Vi/IV), and allows for spinmanipulation. The dual core provides for increased core compressiondifferential resulting in a high spin for short game shots and a lowspin for driver shots. A discussion of the USGA initial velocity test isdisclosed in Yagley et al., U.S. Pat. No. 6,595,872 for a Golf Ball WithHigh Coefficient Of Restitution, which is hereby incorporated byreference in its entirety. Another example is Bartels et al., U.S. Pat.No. 6,648,775 for a Golf Ball With High Coefficient Of Restitution,which is hereby incorporated by reference in its entirety.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changes,modifications and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claims. Therefore, the embodiments of the inventionin which an exclusive property or privilege is claimed are defined inthe following appended claims.

We claim as our invention the following:
 1. A method for forming a corefor a golf ball, the method comprising: mixing a graphene material witha polybutadiene material to form a core mixture, wherein the coremixture comprises 40-90 weight percent of polybutadiene, 0.4 to 2.5weight percent graphene material, 10-50 weight percent zinc diacrylate,1-30 weight percent zinc oxide, and 0.1-10 weight percent peroxideinitiator, wherein the graphene material has a surface area ranging from150 m²/g to 1000 m²/g; and compression molding an outer core from thecore mixture around an inner core to form a dual core.
 2. The methodaccording to claim 1 wherein the dual core has a diameter ranging from0.70 inch to 1.6 inch.